Lissoclinum agriculum, Kott, 2005

Kott, Patricia, 2005, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (Part 3), Journal of Natural History 39 (26), pp. 2409-2479 : 2459-2460

Lissoclinum agriculum sp. nov.

( Figures 12A , 17D )

Distribution

Type locality: Western Australia (east of Montebello I., 7–8 m, coll. S. SlackSmith and L. Marsh, 2 December 1979, syntypes WAM 179.93 ) .

Description

The syntype colonies are small (to 1 cm maximum dimension) soft cushions with spicules throughout the test. A large horizontal common cloacal cavity (the whole depth of the zooids) containing symbiotic Prochloron cells (0.06–0.07 mm diameter) is in the centre of the colony and a sessile common cloacal aperture is on the upper surface of the colony. Spherical dark cells (0.14 mm diameter) are in the test and cluster around the zooids. The spicules (to 0.034 mm diameter) are globular, burr-like with numerous rod-shaped rays. Zooids cross the common cloacal cavity in independent strands of test. They have two testis follicles and the usual straight vas deferens. Larvae are not present.

Remarks

In the form of the colonies and spicules and the presence of Prochloron symbionts in the common cloacal cavity this species resembles Lissoclinum bistratum ( Sluiter, 1909) . The present species differs in the presence of dark cells in the colony test, the size of the spicules (significantly smaller than those of L. bistratum ) and the presence of two testis follicles (rather than the undivided test of L. bistratum ). The species more closely resembles those species of Lissoclinum that have dark test cells around the outside of the zooids and two testis follicles, such as L. badium F. and C. Monniot, 1996, rather than other Lissoclinum symbioses such as L. bistratum and L. timorense ( Sluiter, 1909) . Previously undescribed, the present species is an addition to the list of didemnid/ Prochloron symbioses (see Kott 2001).

Figures

Figure 12. (A) Lissoclinum agriculum sp. nov. (WAM 179.93, syntypes): abdomen. (B–D) Lissoclinum clavatum (SAM E3260, holotype): (B) colony surface; (C) thorax; (D) abdomen. Scale bars: 0.1 mm (A, C, D); 1.0 mm (B).

Figure 17. Scanning electron micrographs of the calcareous spicules of: (A) Trididemnum dispersum (WAM 1044.89); (B) Trididemnum nobile (SAM E3262); (C) Trididemnum pigmentatum (QM G308714); (D) Lissoclinum agriculum sp. nov. (WAM 179.93, syntypes); (E) Lissoclinum bistratum (WAM 1018.89); (F) Lissoclinum clavatum sp. nov. (SAM E3260, holotype); (G) Lissoclinum coactum (WAM 120.90); (H) Lissoclinum diversum (WAM 153.86).